"It's one of the more popular culture wars in the free software community: GUI versus CLI (graphics versus the command-line). Programmers, by selection, inclination, and long experience, understandably are attracted to textual interactions with the computer, but the text interface was imposed originally by technological limitations. The GUI was introduced as a reply to those problems, but has undergone very little evolution from 1973 (when it was invented at Xerox PARC) to today. So why can't we do better than either of these tired old systems?"

My idea: What if we could incorporate CSS into GUIs outside the browser?

Since the only people who really take CSS seriously are web designers (the ones who create the blog websites with text gradient logos using CSS and Photoshop, among other features), what if we let the CSS folks work on the GUIs of applications outside the browser?

CSS, as a young stylesheet language, is engineered towards design and presentation of any markup-based web interface (XHTML, SVG, XUL, etc). Furthermore, the future iterations of CSS, like the CSS3 working draft, are being developed to give the web designers more say in the presentation of their websites, even though they are a long way from usurping some of the roles that web developers (those who use JavaScript frameworks like jQuery and Prototype) currently possess.

I know that, as of 2008, only Firefox-based browsers (using the Stylish extension) have the ability to customize the browser's own interface using CSS "userstyles", even though it goes only so far. This is because of Mozilla's XUL (XML User Interface Language) framework, which supports most other standards that are compatible with the XML standard.

Giving CSS designers control over the GUIs of applications, IMO, will allow for the development of better, more intuitive user interfaces. It's a natural evolution for graphical interfaces, that they should be designed (within the constraints of the programmers, of course).